Due to recent development in communication technology, various data services have been developed and provided. Especially, due to the transition from analog to digital, broadcasting services have evolved to provide data services in an existing communication field, in addition to the support of various contents.
Recent smart TVs claim to support functions of freely retrieving and executing open contents or services over the Internet as well as services provided by broadcasters Accordingly, in order to retrieve various contents and services, Internet Protocol Television (IPTV), Internet TV, and smart TV operators tend to replace a service retrieval technology focusing on broadcasting with a web retrieval technology or extensible MarkUp Language (XML) type technology. Especially, TV-Anytime (TVA) has been used as a reference specification in many domestic and foreign standards, and also specifications of domestic IPTV and Digital Multimedia Broadcasting (DMB) are made with reference to the reference specification.
To provide a description through an example of TVA, the structures and tables of documents is defined for service retrieval information which is expressed with XML. Accordingly, definitions of various services and contents such as broadcasting, video on demand (VOD), and application are provided.
The XML based service retrieval information is described based on text, and thus has a great size of documents and a great amount of accessed information. Especially, broadcast services additionally support VOD or open contents, and thus efficient encoding and decoding methods are required for information such as the XML based service retrieval information in TVA.